This application is based on application Nos. 11-181433, 11-181442 and 11-180544 filed in Japan, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to image correction of color image.
2. Description of Prior Art
In an image processor, a color image is generally subjected to image correction. Various types of correction such as color balance control or color correction are performed.
Color fog is a phenomenon where a particular color covers an image so as to degrade color balance. In a typical example, it is observed when an object is captured under a fluorescent light without using a strobe light. Color fog is observed in many situations.
In order to recover normal color balance, it is known in image processing to convert the brightest portions to white and the darkest portions to black. This technique is simple, but effective. However, in many exceptional cases it may cause a reverse effect or has no effect.
In some image processing, color fog may be checked automatically at a step before the correction. However, when colors are checked automatically, erroneous decisions happen for an image such as a sunset scene or a photograph adopting intentional color representation.
In prior art image correction, contrast is corrected first, and color balance is adjusted next. In many cases, color balance can be adjusted mainly by correcting only contrast. Then, color balance is adjusted in an interactive way to a degree that the color balance is not anomalous when viewed with eyes. It is desirable that an image can be corrected automatically. However, there remain many problems on automatic processing.
An object of the present invention is to control color balance of an image more effectively in image processing.
Another object of the present invention is to check color fog in a user-friendly way in the image processing.
A further object of the present invention is to perform automatic image correction more effectively.
In one aspect of the invention, in the image processing of color image, color image data are received, and the color image data are corrected to maximize an overlapping quantity of histograms of the image data on a plurality of colors.
In another aspect of the invention, in the image processing of color image, color image data are received, and histograms of a plurality of colors on the color image data are calculated. Then, color deviation of image is corrected to maximize an overlapping quantity of the histograms.
In a different aspect of the invention, in the image processing of color image, color image data are received, and color fog is detected on the color image data and a color of the color fog is determined. Then, the image data of the color on which color fog is detected is decreased.
In a still different aspect of the invention, in the image processing of color image, color fog is detected in an input color image data; and a color of the detected color fog is displayed.
In a further aspect of the invention, in the image processing of color image, color fog of input image is corrected first, and contrast on the image is corrected next
An advantage of the present invention is that automatic correction is more successful.